Heat transfer roll body

ABSTRACT

A temperature controlled roll mechanism such as in a supercalender for a paper machine with a first roll having an outer covering of composition having an upper temperature limit and a second opposed heated roll, and the first roll being maintained within its permissible temperature range by having an inner shell coaxially within an outer shell defining a thin annular coolant chamber with passages through the shell and coolant supplied from the space within the inner shell and coolant exhausted through a passage connected only at one end of the annular chamber.

United States Patent [191 Kilmartin Oct. 1, 1974 HEAT TRANSFER ROLL BODYPrimary Examiner-Charles J. Myhre Assistant Examiner-Theo hil W. StreuleJr. 1 h P r [75] i Jo n A Kllmamn Portage Mmh Attorney, Agent, orFirmHill, Gross, Simpson, Van [73] Asslgnee: Beloit Corporation, Beloit,Wis. Sam n, Steadma Chiara & Simpson [22] Filed: Jan. 22, 1973 21 Appl.No.: 325,522 7] ABSTRACT A temperature controlled roll mechanism such asin a supercalender for a a er machine with a first roll [52] US. Cl.165/90 34/124 p p [51] Int Cl Fzsd' 11/02 F28b 5/02 having an outercovering of composition having an [58] i /1 19 upper temperature limitand a second opposed heated roll, and the first roll being maintainedwithin its permissible temperature range by having an inner shell llywithin an outer shell defining a thin annular [56] References Citedcoaxla coolant chamber with passages through the shell and UNITED STATESPATENTS coolant suppliedfrom the space within the inner shell 2,435,9592/1948 Eaby l65/89 nd oolant exhausted through a passage connected g zonly at one end of the annular chamber. I'll e 10 Claims, 3 DrawingFigures is l HEAT TRANSFER ROLL BODY BACKGROUND OF THE INVENTION Thepresent invention relates to improvements in rolls for paper makingmachines and the like, and more particularly to an improved arrangementfor maintaining the temperature of a roll within a permissible limit. Asan example, such a roll is one covered with a composition materialwherein the composition becomes hot with use, and unless cooled, willdeteriorate or become too soft for continued use.

In a super-calender of a paper making machine, for example, one of therolls in a roll couple is frequently covered with a composition materialsuch as material known to the trade as Beltex. The opposing roll will bea polished metal roll which will be heated to a maximum temperature of250F. Relatively high nip pressures are employed in these arrangementson the order of a maximum of I700 pli, and it is essential that thecomposition cover of the one roll not be permitted to reach 250, or itwill soften and deteriorate. It is also essential that when the coveredroll is cooled, that the cooling be uniform so that the temperaturedifferential along the length of the roll does not exceed to Differentarrangements have been employed to attempt to cool the covered roll,such as directing a flow of air through air nozzles at the. coveredroll, but these arrangements have not been wholly satisfactory and havebeen incapable of removing sufficient heat at high op erating speeds.

Another problem which has been faced is with the use of a crowned rollwhich creates a nonuniform temperature in the covered roll, generating ahigher temperature in the middle and at the ends. This is not as seriousas in the case of a cotton filled roll. but in certain covered rolls,the increased temperature in the center will exceed the permissibleoperating level and will change the physical hardness of the roll sothat it is nonuniform throughout its length.

Other efforts to cool such rolls have included inducing a flow ofcoolant into the interior of the filled roll. One difficulty inherentwith such an arrangement is that there has been no way to obtain uniformcirculation of the coolant which tends to build up a layer ofnoncirculating fluid against the inner surface of the roll shell. Thisnoncirculating fluid reaches a higher temperature than the fluid layeradjacent to it and any inequality in circulation will result in aninequality in heat removal, and thus nonuniform temperature of the rollcover. Such nonuniform roll cover temperature can cause the roll coverto reach deterioration temperatures or reach a condition of excessivesoftness, or cause a condition of nonuniform resiliency or softnessalong the length of the roll, thus in turn resulting in nonuniformcalendering of the web passing through the mp.

It is accordingly an object of the present invention to provide animproved cooling or heat transfer mechanism which is simple and reliablein construction and effectively cools a roll to obtain a uniformtemperature along its length.

A further object of the invention is to provide an improved rollstructure which is cooled by a circulating coolant wherein the quantityof coolant circulated is substantially reduced while still obtainingeffective cooling.

A further object of the invention is to provide an improved cooled rollstructure utilizing a liquid coolant which does not drain to becomeoverheated when it is stopped and wherein the coolant circulatingconstruction is improvedover structures heretofore available.

Other objects, advantages and features will become more apparent, aswill equivalent structures which are intended to be covered herein, withthe teaching of the principles of invention in the disclosure of thepreferred embodiment thereof in the specification, claims and drawings,in which:

DESCRIPTION OF THE DRAWINGS FIG. I is a somewhat schematic verticalsectional view taken through a roll assembly constructed in accordancewith the principles of the present invention;

FIG. 2 is a fragmentary enlarged view showing details of the rollconstruction; and

FIG. 3 is a sectional view taken substantially along line IIIIII of FIG.1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated in FIGS. 1 and2, a roll mechanism is shown including a first roll 10, forming apressure nip with a second roll 11. The construction provides asuper-calender wherein a paper web is passed through the nip to becalendered. While advantages are obtained in this particular environmentof the invention, it will be understood that certain features of theinvention may be utilized in other arrangements, but for thisdescription, the structure will be described as used in a paper machine.

The roll 1 l is heated to a temperature of on the order of 250F. Thistemperature is too hot for the resilient composition covering 13 of theroll 10. The roll 10 has a roll shell 12 of metal which provides a rigidbase on which the covering material 13 is supported. For cooling thecovering material 13, heat is transmitted through the metal base 12 tobe removed by a coolant in a manner which will be described.

For supporting the roll 10 in rotation, disks l4 and 15 are pressed intothe ends of the roll shell, and these disks carry journals l6 and 17 tobe supported in bearings for rotatably carrying the roll 10.

Coaxially mounted within the outer shell 12 is an inner shell 18. Thisinner shell defines a thin annular chamber 20 between its outer surfaceand the inner surface of the outer shell 12. Coolant is delivered andmaintained in an axial flow through the thin annular chamber 20 by beingadmitted through a pluralityof openings 19 through the inner shell.These openings 19 are constructed so that a greater flow is receivedinto the end 200 of the annular chamber than the end 20b. The end 20b isadjacent coolant exhaust passages 23 through which the coolant isremoved from the chamber 20. In other words, a greater amount of coolantis admitted to the annular chamber 20 at the end 20a which is remotefrom the coolant exhaust passages 23 than in the end 20b which isadjacent the coolant ex haust passages 23. In a preferred arrangement,the openings are arranged uniformly annularly around the inner shell anduniformly spaced in an axial direction. The diameter or size of the.openings, however, becomes progressively larger at a greater distancefrom the exhaust passages 23. In other words, the diameter of theopenings D is greater than the diameter of the openings D. Thisconstruction provides a controlled flow for controlled heat removal fromthe outer shell. This controlled flow permits a greater change in fluidtemperature without objectionable variations in temperature across theroll face. This also permits a low rate of flow which is desirable.

The exhaust passages 23 are conveniently drilled to extend radiallyinwardly from the annular chamber 20 and communicate with an annularpassage 24 leading out through the journal 16. A line 24a is connectedto the annular passage and contains a pressure control valve 25. This isset at a low pressure sufficient only to prevent the drainage of coolantliquid from the annular chamber 20 when the roll stops. In other words,the valve 25 prevents drainage due to gravity.

Coolant is delivered to the inner chamber 21 within the inner shellthrough a line 26 connecting to a hollow coaxial passage 22 through thejournal 16. Coolant is delivered through the line 26 by pump 27. Thus,the flow of coolant into and out of the roll is conveniently arrangedthrough coaxially located passages.

For controlling the temperature of the outer roll shell, the temperatureof the coolant may be measured such as by a device located at 28 in theline 24a. This coolant detection device may be connected to control theoperation of the pump 27 so that coolant is delivered at a rate tomaintain a uniform predetermined temperature for the roll cover 13.

FIG. 2 shows in somewhat greater detail the relative location of certainof the elements. The disk 14 is formed with a bevelled face 14a on itsinner edge so that it coaxially seats the inner shell 18. The end of theinner shell 18a seats so as to prevent leakage of coolant. The disk head14 has an annular surface 14b to provide a flow space for coolantflowing through the exhaust passage 23.

As shown in FIG. 2, the holes 19 in the inner shell are countersunk, asin 19a, from their outer surface to prevent clogging of the openings. v

The openings are so arranged, as above stated, by size so that a greateramount of fluid is passed across the inner surface of the outer shellfor the longest distance between the large openings and the exhaustport, while a lesser amount flows from the inner chamber through smallerholes nearer to the exhaust port. This lesser amount of fluid remains inthe heat transfer chamber for a shorter period of time. This results ina relatively even temperature level in the fluid across the entire rollface.

The annular coolant chamber must be maintained relatively thin andpreferably on the order between one-eighth to. one-fourth inch thick. Asan example of a size relationship which is well suited, is a chamberwhich is three-sixteenth inch radial dimension. The holes leading intothe space are arranged sequentially larger away from the exhaust opening23. For example, if five holes are used along the length of the rollshell, the holes may be on the order of 3/32, Vs, /32, 3/16 and 541 inchin diameter. The size of the inlet and exhaust passages are notcritical, except they must be sufficiently large to carry maximumcoolant flow, and an inlet pipe on the order of 1 inch is well suitedfor the above dimensioned openings. The exhaust ports may be on theorder of inch diameter with a plurality of ports provided uniformlycircumferentially spaced with 8 exhaust ports being used.

While the foregoing description refers to the delivery of coolant fluid,in order to carry away heat from the roll shell, it will be understoodthat the principles of the invention can fully be used for circulationof a heating liquid. Where the roll shell is to be heated a liquid willbe circulated which is heated to a predetermined temperature to conveyheat to the roll shell. It will be understood that the concepts of theinvention herein disclosed are not to be limited to either heating or tocooling.

I claim as my invention:

1. A temperature controlled roll mechanism for a paper machine or thelike comprising in combination:

a first roll having a roll shell with an inner rigid metal annular baseand a covering of a composition having an upper temperature limit;

a second opposing heated roll forming a roll couple with the first rolland being heated to heat the outer layer of said first roll;

end journals for the first roll for supporting the roll for rotation;

an inner shell positioned coaxially within the outer shell and defininga thin annular chamber therebetween and forming a hollow fluid receivinginner chamber within the inner shell;

a plurality of axially spaced openings through said inner shell leadingfrom said inner chamber to said annular chamber;

a coolant delivery mechanism connected to said inner chamber;

and a coolant exhaust passage connected to one end of said annularchamber receiving flow from said axially spaced openings so that fluidflows axially through the annular chamber to said exhaust passage.

2. A temperature controlled roll mechanism for a paper machine or thelike constructed in accordance with claim 1:

wherein said openings are constructed so that a greater volume of flowpasses from the inner chamber to the annular chamber at the end remotefrom said exhaust passage than at the end adjacent said exhaust passage.

3. A temperature controlled roll mechanism for a paper machine or thelike constructed in accordance with claim 1:

wherein said openings are larger at the end of said inner shell remotefrom the exhaust passage than at the end adjacent said exhaust passage.

4. A temperature controlled roll mechanism for a paper machine or thelike constructed in accordance I with claim 1:

including a pressure relief valve in said exhaust passage maintainingcoolant within the annular chamber and preventing gravity drainage ofthe coolant from said annular chamber.

5. A temperature controlled roll mechanism for a paper machine or thelike constructed in accordance with claim 1:

wherein said coolant delivery mechanism includes an axial flow passageinto said inner shell coaxially arranged with said coolant exhaustpassage.

6. A temperature controlled roll mechanism for a paper machine or thelike constructed in accordance with claim 1:

wherein said journals are supported on circular disks positioned in eachend of said roll shell.

7. A temperature controlled roll mechanism for a paper machine or thelike comprising in combination:

means for delivering said fluid to the inner chamber of said innershell;

and a fluid exhaust passage leading from one end of said annular chamberso that the fluid flows axially in the annular chamber to said one end.

8. A temperature controlled roll mechanism for a paper machine or thelike constructed in accordance with claim 7:

wherein said openings are constructed for a greater volume of flow intosaid annular chamber at the end of the inner shell remote from theexhaust passage than adjacent the exhaust passage.

9. A temperature controlled roll mechanism for a paper machine or thelike constructed in accordance with claim 7:

wherein said journal members have circular disks mounted within saidouter roll shell with said exhaust passages being within one of saiddisks.

10. A temperature controlled roll mechanism for a paper machine or thelike constructed in accordance with claim 1:

wherein said annular chamber has a radial dimension in the range ofone-eighth to one-quarter inch. =l=

1. A temperature controlled roll mechanism for a paper machine or thelike comprising in combination: a first roll having a roll shell with aninner rigid metal annular base and a covering of a composition having anupper temperature limiT; a second opposing heated roll forming a rollcouple with the first roll and being heated to heat the outer layer ofsaid first roll; end journals for the first roll for supporting the rollfor rotation; an inner shell positioned coaxially within the outer shelland defining a thin annular chamber therebetween and forming a hollowfluid receiving inner chamber within the inner shell; a plurality ofaxially spaced openings through said inner shell leading from said innerchamber to said annular chamber; a coolant delivery mechanism connectedto said inner chamber; and a coolant exhaust passage connected to oneend of said annular chamber receiving flow from said axially spacedopenings so that fluid flows axially through the annular chamber to saidexhaust passage.
 2. A temperature controlled roll mechanism for a papermachine or the like constructed in accordance with claim 1: wherein saidopenings are constructed so that a greater volume of flow passes fromthe inner chamber to the annular chamber at the end remote from saidexhaust passage than at the end adjacent said exhaust passage.
 3. Atemperature controlled roll mechanism for a paper machine or the likeconstructed in accordance with claim 1: wherein said openings are largerat the end of said inner shell remote from the exhaust passage than atthe end adjacent said exhaust passage.
 4. A temperature controlled rollmechanism for a paper machine or the like constructed in accordance withclaim 1: including a pressure relief valve in said exhaust passagemaintaining coolant within the annular chamber and preventing gravitydrainage of the coolant from said annular chamber.
 5. A temperaturecontrolled roll mechanism for a paper machine or the like constructed inaccordance with claim 1: wherein said coolant delivery mechanismincludes an axial flow passage into said inner shell coaxially arrangedwith said coolant exhaust passage.
 6. A temperature controlled rollmechanism for a paper machine or the like constructed in accordance withclaim 1: wherein said journals are supported on circular diskspositioned in each end of said roll shell.
 7. A temperature controlledroll mechanism for a paper machine or the like comprising incombination: an outer roll shell subjected to an external heat transferenvironment; end journal members for rotatably supporting said roll; aninner shell within the roll shell having an inner chamber and forming athin annular chamber within the outer roll shell; a plurality of axiallyspaced openings through the inner roll shell for the flow of heatexchange fluid from said inner chamber to said annular chamber; meansfor delivering said fluid to the inner chamber of said inner shell; anda fluid exhaust passage leading from one end of said annular chamber sothat the fluid flows axially in the annular chamber to said one end. 8.A temperature controlled roll mechanism for a paper machine or the likeconstructed in accordance with claim 7: wherein said openings areconstructed for a greater volume of flow into said annular chamber atthe end of the inner shell remote from the exhaust passage than adjacentthe exhaust passage.
 9. A temperature controlled roll mechanism for apaper machine or the like constructed in accordance with claim 7:wherein said journal members have circular disks mounted within saidouter roll shell with said exhaust passages being within one of saiddisks.
 10. A temperature controlled roll mechanism for a paper machineor the like constructed in accordance with claim 1: wherein said annularchamber has a radial dimension in the range of one-eighth to one-quarterinch.